The Inertial Upper Stage or IUS is a two-stage solid-fueled booster rocket developed by NASA and the U.S. Air Force for the launching of large payloads from either a Titan III (later Titan IV) rocket or from the payload bay of the Space Shuttle.
The solid-fueled IUS was created as a compromise between the Transtage, which was not powerful enough for most NASA payloads, and the Centaur, which was not needed for all military and intelligence payloads. IUS was powerful enough to deliver two large DoD or NSA satellites into proper orbits over the former Soviet Union, or a single NASA payload (most notably the TDRS (Tracking and Data Relay Satellite) constellation into a geostationary orbit on either the Shuttle or the Titan III.
IUS's first launch was in 1982 on a Titan 34D rocket from the Cape Canaveral Air Force Station shortly before the STS-6 mission. Boeing was the primary contractor for the IUS Chemical Systems Division of United Technologies built the IUS solid rocket motors
|#||Launch Date||Launch Vehicle||Payload||Notes|
|1||October 30, 1982||Titan 34D||DSCS-II F16|
|Mission successful despite telemetry loss for most of the flight.|
|2||April 4, 1983||STS-6||TDRS A||Second stage tumbled due to a control system failure. Over the period of several weeks, ground controllers used excess fuel in the TDRS to move it into proper orbit.|
|3||January 24, 1985||STS-51-C||Magnum 1||Classified DoD payload.|
|4||October 3, 1985||STS-51-J||DSCS-III B4|
|Classified DoD payload.|
|5||January 28, 1986||STS-51-L||TDRS B||Destroyed due to Challenger disaster.|
|6||September 29, 1988||STS-26||TDRS C|
|7||March 13, 1989||STS-29||TDRS D|
|8||May 4, 1989||STS-30||Magellan|
|9||June 14, 1989||Titan IVA||DSP 14|
|10||October 18, 1989||STS-34||Galileo|
|11||November 22, 1989||STS-33||Magnum 2||Classified DoD payload.|
|12||October 6, 1990||STS-41||Ulysses|
|13||November 13, 1990||Titan IVA||DSP 15|
|14||November 15, 1990||STS-38||Magnum 3 or|
Exact payload unknown
|Classified DoD payload.|
|15||August 2, 1991||STS-43||TDRS E|
|16||November 24, 1991||STS-44||DSP 16|
|17||January 13, 1993||STS-54||TDRS F|
|18||December 22, 1994||Titan IVA||DSP 17|
|19||July 13, 1995||STS-70||TDRS G|
|20||February 23, 1997||Titan IVB||DSP 18|
|21||April 9, 1999||Titan IVB||DSP 19||Spacecraft failed to separate from the second IUS stage.|
|22||July 23, 1999||STS-93||Chandra X-ray Observatory|
|23||May 8, 2000||Titan IVB||DSP 20|
|24||August 6, 2001||Titan IVB||DSP 21|
|25||February 14, 2004||Titan IVB||DSP 22|
Boeing Defense and Space Group.(Inertial Upper Stage boosters with Titan IV-B launch vehicles)(Defense Contracts)
Sep 22, 1997; * Boeing Defense and Space Group, [BA] Seattle, Wash., is being awarded a $152.3 million cost-plus-award-fee contract to provide...
Boeing Space and Missile Group. (Inertial Upper Stage vehicles equipment and services contract)(Defense Contracts)
May 04, 1992; * Boeing Space and Missile Group, Seattle, Wash., $46.3 million a fixed-price incentive contract for long lead equipment and...
The Boeing Co. (contract awarded for integration and launch support for the Inertial Upper Stage program)(Defense Contracts)
Sep 29, 1995; The Boeing Co., Seattle, Wash., $31.5 million Cost Reimbursement with Award Fee/Level of Effort contract provided for FY '96...
Boeing Defense and Space Group, Space and Missile Div. (contract increase for work on Inertial Upper Stage launch vehicles) (Defense Contracts)
Nov 03, 1994; Boeing Defense and Space Group, Space and Missile Div., Seattle, Wash., a $68.5 million face value increase to a fixed-...